Warding Energy Lore - will increase the "Ward Efficiency" value (total shield energy points), will improve the "Block Warding Energy" value (damage absorption), and will increase the Shield Regeneration rate when mastered. Note that Warding Energy Mastery (75 spent points) does not enable or increase shield regeneration while in combat; the regeneration speed bonus is applied to out-of-combat shield regeneration only. The Temple Guardian must take the Recharge mod to gain in-combat shield regeneration (which is increased by Tactics Lore).
Tactics Lore - increases the damage from the Derogate mod, increases in-combat Shield Regeneration of the Recharge mod, improves the "Block Warding Energy" value (damage absorption), allows for modification points.
In-Combat Shield Regeneration is listed under the Σ list of modifiers (bonus overview).
The value is 3 + 1/level and is then modified by the +% Damage portion of Tactics Lore.
No other modifiers seem to have an effect on how much shield energy is regenerated while in combat.
Note that, like all CA's in the Devout Guardian aspect, casting speed is determined by weapon speed, and can be boosted by weapon lore skills and +% attack speed. Likewise, the casting speed will be penalized by wielding a weapon with too high a level.
Pros and Cons
Major increase to survivability, especially with Recharge mod
It imposes a steep regeneration penalty to all Combat Arts